DENON PMA-451
¥ 49,800 (around 1977)
Commentary
This pre-main amplifier is equipped with PCC and inherits the technology of PMA 701 and PMA 501.
The PCC (Phono Crosstalk Canceler) is a device that adds reverse crosstalk to the Phono Pickup type crosstalk and cancels it out. By using the attached adjustment record to operate two knobs, it is possible to improve the frequency range most easily perceived by the ear to approximately -40dB.
The power amplifier section is composed of a direct-coupled OCL circuit for all stages of differential amplification. It is composed of a low-impedance power supply circuit, and new power transistors such as double epitaxial structure and triple diffusion structure are adopted for the output final stage respectively.
To protect the speakers from errors and accidents, it has a built-in protection circuit with extremely fast response time and high reliability.
In consideration of the effect on sound quality, we have adopted a relay with a special structure.
In order to improve crosstalk caused by interference between channels, mutual interference is reduced by a circuit configuration in which two circuits are separated, and by disconnecting the power supply of a power circuit with high current and the power supply of a preamplifier circuit with low current.
To prevent the small signal sent from the record player from being degraded by wiring or changeover switches, one phono input circuit is used and the input terminal is directly connected to the equalizer amplifier.
This reduces the shielding wire and stray capacitance and improves the input impedance.
To reduce dynamic crosstalk, the power supply section is a pre-main, separately wound power supply trans configuration.
Model Rating
| Type | Pre-main amplifier |
| Power Amplifier Unit | |
| Circuit system | DC-DC pure complimentary service OCL circuit |
| Dynamic Output (IHF) | 140W (70W + 70W, 8 Ω) |
| Rated Output (Both Channels Driven, Sine Wave Continuous Output) | 45W + 45W (8 ohm, 20 hz to 20 khz) 55W + 55W (4 ohm, 1 khz) |
| Total harmonic distortion factor (Aux in → SP out) | 0.08% or Less (at Rated Output) |
| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | 0.1% or less (at rated output, Aux in → SP out) |
| Output Bandwidth (IHF, both channel drives) | 5 Hz to 50 kHz |
| Output impedance | 0.16 Ω or less |
| Output terminal | Speaker AORb : 4 Ω ~ 16 Ω Speaker A + B : 8 Ω ~ 16 Ω Headphone port |
| Preamplifier Section | |
| Input Sensitivity / Impedance | Phono : 2.5Vrms/50k Ω Tuner, Aux, Tape1, 2 : 150mVrms/85k Ω |
| Phono maximum allowable input (Phono → Rec out) | 150 mVrms or More (1 kHz) |
| Total harmonic distortion rate (1 kHz) | Phono → Rec out : 0.008% or less (at 3 vrms output) 0.1% or Less (Maximum Output) |
| RIAA deviation | 20 Hz to 20 kHz ± 0.3 dB |
| Output Level / Impedance | Rec out : 150mVrms/50k Ω or more |
| Tone control | Bass : 50 Hz ± 10 dB Treble : 20 kHz ± 10 dB |
| <PCC Part> | |
| Maximum allowable input | 9Vrms |
| Post-cancellation phono crosstalk | About -40dB |
| Transmission frequency characteristic | 10 Hz to 50 kHz + 0 -1dB |
| <General> | |
| Transmission frequency characteristic time | 20 Hz to 20 kHz ± 0.75 dB |
| Signal-to-noise ratio (IHF, A-network, input short circuit) | Phono : 75 dB or more Tuner, Aux, Tape1, 2 : 95 dB or more |
| Crosstalk (Phono → SP out) | -75dB or less (20 Hz to 1 kHz) -56dB or less (20 kHz) |
| Power outlet | Switched : 2 systems, total 150W Unswitched-1 line, 100W |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption (Electrical Appliance and Material Control Law) | 125W |
| External dimensions | Width 430x Height 142.5x Depth 310 mm |
| Weight | Approx. 10.5 kg |
| Attachment | Record for reconciliation |